Self-locking pin

ABSTRACT

A self-locking pin having a shaft, a headed end, and detent means biased in a bore in the pin. The portion of the detent or plunger that extends outwardly from the bore is wedge-shaped, while the portion of the plunger disposed inside the bore is cylindrical. A transitional angle is formed at the point where the configuration of the plunger changes from cylindrical to wedge-shaped. The transitional angle defines shoulders on either side of the plunger. The shaft is staked at points along the perimeter of the bore so that the inwardly extending surface created by the staking abuts the shoulders and prevents the plunger from rotating or being removed from the bore. In an alternate embodiment, the plunger may be rotated to a locked depressed position.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] The invention relates to fasteners, namely threadless fastenersand more particularly to a threadless fastener for retaining two or morestructures through apertures formed in each structure.

[0003] Detent pins are well known in industry. Many of these pins fallinto the category of safety bolts. Safety bolts have a threaded end towhich a nut can be attached to as well as a detent mechanism along thelength of the bolt. The main fastening mechanism in safety bolts isthreading the nut on the end of the bolt. These products are often usedin the aircraft industry so an extra safety factor is present in casevibrations cause the nut to loosen or someone forgets to tighten thenut. The detent mechanism is this extra safety factor. However, thesedual fasteners make safety bolts more difficult and thus more expensiveto manufacture. Additionally there are some applications where such abolt cannot be used because it is either impractical or impossible toaccess the threaded end of the bolt after it is inserted through anaperture. Also, screwing the nut on the end of the bolt causes anincrease in assembly time.

[0004] Cotter pins are also well known in industry. A bolt with a cotterway is inserted through an aperture. A cotter pin is then insertedthrough the cotter way so the bolt cannot be removed from the aperture.It is thus obvious that access to the backside of the workpiece isnecessary for a cotter pin to be utilized. Here again, insertion of thecotter pin in the cotter way is an extra step that will take more timeduring assembly.

[0005] There is a need in the market for a self-locking pin which issimple to manufacture and can be installed with little effort and inapplications where there is no access to the opposing side of theworkpiece and thus a nut cannot be applied to the threaded end of a pin.

[0006] 2. Description of Prior Art

[0007] One type of prior art bolt is disclosed in U.S. Pat. No.4,759,671 to Duran. Duran discloses a self-retaining bolt assembly inwhich the detent is a solid spherically shaped ball element with cut outsections and these cut out sections must be configured to saddleprotuberances in the hole to prevent rotation. The periphery of the holeis peened in order to retain the detent in the hole. The shaft anddetent of this bolt must both be machined carefully to assure a properfit and retention for the detent.

[0008] Another prior art bolt is disclosed in U.S. Pat. No. 3,561,516 toReddy. Reddy discloses a bolt with diametrically opposed detentsslidably disposed in one hole. Each detent has a lateral passage with asloped cam surface. These sloped cam surfaces engage a cam member whichretains the detents in the hole. The detents are pulled into the holewhen a force is exerted on the cam surface of the cam member by the camsurfaces of the detents. The detents are moved outwardly by the biasingmeans disposed between the detents. A number of carefully machinedparts, which are difficult to install properly, are required.Additionally, the passageway extending along the axis of the boltweakens the bolt.

[0009] A prior art bolt is disclosed in U.S. Pat. No. 2,361,491 toNagin. Nagin disclosed a detent, generally circular in section, with a45-degree slope at the upper end. A V-shaped groove with plane cam facesis formed in the body of the detent. The detent is slidably disposed ina hole in the shank. A circular passage extends along the bolt axis. Apin is slidably disposed in this passage. The pin is biased with aspring to engage the V-shaped groove and retain the detent in the hole.This bolt also must be carefully machined and installed to operatecorrectly. Additionally the passage in the shaft weakens the bolt.

SUMMARY OF THE INVENTION

[0010] The present invention, a self-locking pin, provides a pin with auniquely shaped detent or plunger, which facilitates easy installationof the pin through an aperture in an object. In addition, the novelplunger in combination with a staking process non-rotatably retains thedetent in its hole.

[0011] In one embodiment the self-locking pin has an elongated shaftwith a first end and a second headed end. The shaft has a hole bored init with a plunger slidably disposed in the hole. The plunger has a lowercylindrical portion and an upper wedge-shaped portion. A shoulder isformed on the lateral sides of the plunger where these two portionsmeet. The plunger is biased in the hole. The shaft of the pin is stakedon lateral sides of the plunger with a perpendicular radius punch toretain the plunger in the hole. The location of the staking correspondsto the plunger's shoulders.

[0012] In an alternate embodiment, the plunger is formed with shoulderson its leading and trailing sides. In this embodiment, the shaft is thenstaked on the leading and trailing sides of the plunger.

[0013] In yet another embodiment, the plunger is formed with a shoulderonly on its trailing side. In this embodiment, the shaft is staked onthe trailing side of the plunger.

[0014] In a final embodiment, the hole is bored through the entireshaft. Two plungers are then disposed in the hole and each opening tothe hole is staked on lateral sides of the plungers.

[0015] The plunger can have different shapes depending upon theapplication. Another alternate embodiment includes a plunger that can belocked in its depressed position allowing the pin to be freely insertedor removed until the plunger is unlocked.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a perspective view of a pin in accordance with theinvention.

[0017]FIG. 2 is an exploded perspective view of the pin in FIG. 1.

[0018]FIG. 2A is an alternate exploded perspective view of the pin inFIG. 1.

[0019]FIG. 2B is another alternate exploded perspective view of the pinin FIG. 1.

[0020]FIG. 2C is yet another alternate exploded perspective view of thepin in FIG. 1.

[0021]FIG. 3 is a top plan view of the pin of FIG. 1.

[0022]FIG. 4 is a side elevation view of the pin of FIG. 1.

[0023]FIG. 5 is an end elevation view of the pin of FIG. 1.

[0024]FIG. 6 is a cross sectional view of the pin of FIG. 3 taken alongline 6-6 of FIG. 3.

[0025]FIG. 7 is a top plan view of the wedge-shaped plunger of FIG. 2.

[0026]FIG. 8 is a front elevation view of the wedge-shaped plunger ofFIG. 7.

[0027]FIG. 9 is a side elevation view of the wedge-shaped plunger ofFIG. 8.

[0028]FIG. 10 is an exploded perspective view of an alternate embodimentof the pin of FIG. 1 with a spring retaining cavity.

[0029]FIG. 11 is a perspective view of an alternate embodiment of thewedge-shaped plunger of FIG. 2.

[0030]FIG. 11A is a perspective view of another alternate embodiment ofthe wedge-shaped plunger of FIG. 2.

[0031]FIG. 12 is a perspective view of a double-wedged embodiment of theplunger.

[0032]FIG. 12A is a perspective view of a conical embodiment of theplunger.

[0033]FIG. 12B is a perspective view of a radiused embodiment of theplunger.

[0034]FIG. 13 is a cross sectional view of an alternative embodiment ofthe pin with two wedge-shaped plungers taken along line 13-13 of FIG.16.

[0035]FIG. 14 is a perspective view of the pin of FIG. 1 using thewedge-shaped plunger of FIG. 11.

[0036]FIG. 15 is a perspective view of the pin of FIG. 1 using thewedge-shaped plunger of FIG. 11A.

[0037]FIG. 16 is a perspective view of the pin of FIG. 13.

[0038]FIG. 17 is a side elevation view of the pin of FIG. 1 installed inan aperture through a panel.

[0039]FIG. 18 is a perspective view of another alternate embodiment pin,similar to the pin shown in FIG. 14.

[0040]FIG. 19 is a perspective view of the alternate embodiment pinshowing the plunger being locked.

[0041]FIG. 20 is a perspective view of the alternate embodiment pin withthe plunger locked.

[0042]FIG. 21 is a cross-section view taken along line 21-21 of FIG. 20showing the locked plunger.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0043] Although the disclosure hereof is detailed and exact to enablethose skilled in the art to practice the invention, the physicalembodiments herein disclosed merely exemplify the invention, which maybe embodied in other specific structure. While the preferred embodimenthas been described, the details may be changed without departing fromthe invention, which is defined by the claims.

[0044]FIG. 1 illustrates the presently preferred embodiment of theself-locking pin 20 according to the invention. The pin 20 has agenerally cylindrical shaft 22 with a first end 24 and a second end 26.The second end 26 may have an enlarged head 28.

[0045] As seen in FIG. 2, a re-entrant bore 30 extends partway thoughthe shaft 22 near the first end 24. The bore 30 extends radiallyinwardly towards the axis of the shaft. The bore 30 may or may notintersect the central longitudinal axis of the shaft. A plunger 32 isslidably disposed in the bore 30. The plunger 32 has a cylindricalportion 34 and a wedge-shaped portion 36. The plunger sits upon ahelical coil spring 54., As shown in FIG. 2A, a leaf spring 70 may beused as the biasing means. As shown in FIG. 2B, compressible material 72may be used as the biasing means. As shown in FIG. 2C, an elasticmaterial 74 may be utilized as the biasing means.

[0046]FIGS. 3, 4, and 5, show views of the pin 20 from the top, side,and end respectively.

[0047]FIG. 6 shows a cross section of the pin 20. This illustrates thespring 54 biasing the plunger 32. While the preferred embodiment uses ahelical coil spring, other acceptable biasing means such as, but notlimited to, a leaf spring, or a cushion of sufficiently elastic materialcould be utilized.

[0048] The plunger 32 can either sit directly on top of the spring 54,or a cavity 56 can be counter-bored in the bottom surface of the plunger32 to act as a spring seat and retain the spring 54. The phantom linesin FIG. 10 denote this cavity 56.

[0049] The preferred embodiment of the plunger is further illustrated inFIGS. 7, 8, and 9. The plunger 32 has a transitional angle 38 at thepoint where the configuration of the plunger 32 changes from cylindrical34 to wedge-shaped 36. This transitional angle 38 forms a taperedshoulder 40. As will be described hereinafter, the shoulder 40 helpsretain the plunger 32 in the bore 30. Referring to FIG. 9, the side ofthe wedge-shaped portion proximate to the first end 24 of the pin 20 isthe wedge leading side 42. The side of the wedge-shaped portionproximate to the second end 26 of the pin 20 is the wedge trailing side44. As seen in FIG. 8, the wedge also has oppositely disposed lateralsides 46. In the preferred embodiment, shoulders 40 are formed on eachof the lateral sides 46 of the plunger 32. An abutment 50 is formed onthe side opposite leading side 42.

[0050] As can be best seen in FIGS. 1 and 4, when the plunger 32 is inits normal position in the bore 30, the cylindrical portion 34 residesbelow the surface of the shaft 22 and the wedge-shaped portion 36extends above the surface of the shaft 22. Referring to FIGS. 4 and 9,the wedge leading side 42 of the plunger 32 is proximate the surface ofthe shaft 22. The top surface of the plunger 32 extends angularlyupwardly away from the surface of the shaft 22 to define a rampedengaging surface 48 and the abutment 50. The abutment 50 isperpendicular or normal to the axis of the shaft 22 and faces thedirection of the second end 26.

[0051] The plunger 32 and shaft 22 could be made from any suitablematerials such as, but not limited to, alloy steels, carbon steels,stainless steel, or aluminum alloys.

[0052] To assemble the self-locking pin 20, the spring 54 is firstplaced in the re-entrant bore 30. Next, the plunger 32 is placed in thebore 30 in the correct orientation. The pin 20 is held in place, withthe plunger 32 in its depressed position, by one tool while another toolpunches the shaft 22 using a radius stake punch perpendicular to the pin20. The staking 52 causes a change in the shape of the shaft 22 aroundthe entrance to the bore 30. The smooth round bore 30 is formed to asubstantially oval shape with some depth as best shown in FIGS. 2 and 3.In the preferred embodiment, the shaft 22 is staked on the lateral sidesof the wedge. The staking 52 forms inwardly extending marginal portions.This is best shown in FIG. 10. These inwardly extending portions abutthe shoulder 40 of the plunger 32 (see FIGS. 7 through 9) as the spring54 urges the plunger 32 outwardly of the bore 30. The edge of thestaking 52 abuts the flat lateral sides 46 and surface 40 of the plunger32 and prevents the plunger 32 from rotating or being removed from thebore 30. Alternately, and as shown in FIGS. 14 and 15 respectively, asingle stake may be placed behind the plunger or a pair of stakes may beplaced in front of and behind the plunger.

[0053]FIGS. 11 and 11A show first alternate embodiments of the plunger.The plunger 132 embodied in FIG. 11 has a transitional angle 138 on onlythe wedge trailing side 144. This creates only one shoulder 140, whichis located on the wedge trailing side 144. Using this plunger 132embodiment, the shaft 22 is preferably staked only on the plungertrailing side as shown in FIG. 14.

[0054] The plunger 232 embodied in FIG. 11A has transitional angles 238on both the wedge trailing side 244 and the wedge leading side 242. Thiscreates shoulders 240 on both the wedge trailing side 244 and the wedgeleading side 242. Using this plunger 232 embodiment, the shaft ispreferably staked on both the wedge trailing side 244 and the wedgeleading side 242 as shown in FIG. 15.

[0055]FIGS. 12, 12A and 12B show other alternate embodiments of theplunger. FIG. 12 depicts a double-wedge plunger 332 having oppositeramped engaging surfaces 348, 350 that meet at an edge 352. FIG. 12Ashows a conical plunger 432 terminating at a point 434 and FIG. 12Bdepicts a radiused plunger 532 having a smooth, domed top 534. It is tobe understood that any of the plungers could be staked in any of thepins as described.

[0056]FIGS. 13 and 16 show an alternate embodiment of the self-lockingpin 20 in which two plungers 132 are utilized. As shown in FIG. 13, thetwo plungers 132 are disposed in one bore 30. The plungers 132 areseparated by a spring 54, biasing each plunger 132 in an outwarddirection. Each plunger 132 is of the preferred embodiment of theplunger 132. The shaft 22 is staked on the lateral sides 46 of eachplunger 132.

[0057]FIG. 17 shows the self-locking pin 20 inserted through anaperture. In regular use, the self-locking pin 20 is inserted through anaperture in at least one object with a restraining surface 60. Theramped engaging surface 48 of the plunger 32 abuts the inner surface 62of the aperture. The force of the inner surface 62 of the apertureagainst the ramped engaging surface 48 of the plunger 32 causes theplunger 32 to be pushed inwardly against the bias of the spring 54 intothe bore 30 until the abutment 50 is no longer exposed. The pin 20 canthen be installed completely by continuing to push the pin 20 throughthe aperture. Once the pin 20 is installed and the ramped engagingsurface 48 clears the aperture the plunger 32 pops back up against thebias of the spring 54. As shown in FIG. 17, the flat abutment 50 of theplunger 32 abuts the restraining surface 60 of the object, preventingthe pin 20 from being withdrawn from the aperture in a similar manner.

[0058]FIGS. 18 through 21 show an alternate embodiment of theself-locking pin 20 further including a lockable plunger 80. Plunger 80includes a recess 82 formed in its ramped engaging surface 48 forreceiving a tool T. A single stake 52 is placed behind the plunger 80.When partially depressed (typically with the use of the tool) theplunger 80 may be rotated, as shown in FIG. 19. The rotation allowsplunger 80 to be trapped beneath the stake 52 and therefore hold theplunger in a depressed or retracted position (see FIG. 21). Rotating theplunger 80 in either direction allows the plunger to return to itsformer position where it can be freely depressed and extended.Alternately, the orientation of the plunger may be changed by onehundred eighty degrees (180 degrees).

[0059] The foregoing is considered as illustrative only of theprinciples of the invention. Furthermore, since numerous modificationsand changes will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationshown and described. While the preferred embodiment has been described,the details may be changed without departing from the invention, whichis defined by the claims.

1. A self-locking pin comprising; an elongated shaft; at least onecylindrical re-entrant bore intersecting said shaft; at least oneplunger, said plunger including a cylindrical portion slidably disposedin said bore and a wedge-shaped portion extendable outwardly of saidre-entrant bore, said wedge-shaped portion including a laterallyextending, substantially planar surface; biasing means disposed in saidre-entrant bore, and biasing said plunger outwardly of said bore; saidshaft being staked on at least one side of the entrance of saidre-entrant bore to provide a marginal surface extending angularlyrelative to the longitudinal axis of said shaft, and further beingengagable with said planar surface to thereby restrain said plunger fromrotation within said bore.
 2. (cancelled)
 3. A self-locking pin asclaimed in claim 1 wherein said shaft has a first end and a second end.4. A self-locking pin as claimed in claim 1 wherein the longitudinalaxis of said re-entrant bore extends radially inwardly and substantiallyperpendicular to the longitudinal axis of said shaft.
 5. (cancelled) 6.A self-locking pin as claimed in claim 3 wherein said second endcomprises an enlarged headed portion.
 7. A self-locking pin as claimedin claim 1 wherein said biasing means comprises a helically woundcompression spring.
 8. A self-locking pin as claimed in claim 1 whereinsaid biasing means comprises a leaf spring.
 9. A self-locking pin asclaimed in claim 1 wherein said biasing means comprises a compressiblematerial.
 10. A self-locking pin as claimed in claim 1 wherein saidbiasing means comprises an elastic material.
 11. A self-locking pin asclaimed in claim 7 wherein said plunger includes a spring-retainingcavity in the bottom surface thereof.
 12. A self-locking pin as claimedin claim 8 wherein said plunger includes a spring-retaining cavity inthe bottom surface thereof.
 13. A self-locking pin as claimed in claim 9wherein said plunger includes a material-retaining cavity in the bottomsurface thereof.
 14. A self-locking pin as claimed in claim 10 whereinsaid plunger includes a material-retaining cavity in the bottom surfacethereof.
 15. A self-locking pin as claimed in claim 1, wherein at leasta portion of the surface of said plunger is formed to provide anangularly disposed transitional shoulder portion extending between saidwedge-shaped portion and said cylindrical portion, and wherein saidmarginal surface is engagable with said shoulder portion. 16.(cancelled)
 17. A self-locking pin as claimed in claim 15 wherein saidwedge-shaped portion has a leading edge being positioned closest to thefirst end of said shaft, said leading edge of said wedge-shaped portionbeing proximate to said shaft surface and said wedge-shaped portionextending angularly upward of said shaft to define a ramped abuttingsurface, said ramped abutting surface terminating in an abutment andfacing the second end of said shaft.
 18. A self-locking pin as claimedin claim 17 wherein said plunger has two lateral sides, saidtransitional angle defining shoulders on each lateral side, where saidshaft is staked to provide inwardly extending marginal portions adaptedto abut said shoulders.
 19. (cancelled)
 20. (cancelled)
 21. Aself-locking pin comprising: an elongated shaft including a first endand a second end; at least one cylindrical re-entrant bore intersectingsaid shaft; at least one plunger, said plunger including a cylindricalportion slidably disposed in said bore and a wedge-shaped Portionextending outwardly of said re-entrant bore, and wherein a plungertransitional angle is formed at the configuration of the plunger changesfrom cylindrical to wedge-shaped, said plunger transitional angledefining at least one shoulder peripherally spaced on the plunger; saidwedge-shaped portion has a leading edge being positioned closest to thefirst end of said shaft, said leading edge of said wedge-shaped portionbeing proximate to said shaft surface and said wedge-shaped portionextending angularly upwardly of said shaft to define a ramped abuttingsurface, said ramped abutting surface terminating in an abutment andfacing a second end of said shaft; and further, wherein said plunger hastwo lateral sides, said transitional angle defining shoulders on eachlateral side, where said shaft is staked to provide inwardly extendingmarginal portions adapted to abut such shoulders, and wherein saidself-locking pin includes more than one peripherally spaced re-entrantbores, and wherein each said bore has one plunger slidably disposedtherein.
 22. A self-locking pin as claimed in claim 21 wherein eachplunger has a transitional angle which defines shoulders on each of thelateral sides of said plunger, where said shaft is staked to provideinwardly extending marginal portions adapted to abut said shoulders. 23.(cancelled)
 24. A self-locking pin to be inserted through an aperture inat least one object wherein said object terminates in a restraintsurface to retain the pin in the aperture, said pin comprising: anelongated shaft including a first end and a second end; at least onecylindrical re-entrant bore intersecting said shaft, said bore extendingradially inwardly towards the axis of said shaft; at least one plungerslidably disposed in said bore, said plunger having a cylindricalportion and a wedge-shaped portion, a leading edge of said wedge-shapedportion being positioned closest to the first end of said shaft, saidleading edge of said wedge-shaped portion being proximate to said shaftsurface and said wedge-shaped portion extending angularly upwardly ofsaid shaft surface to define a ramped engaging surface adapted forengagement with the object aperture surface, said ramped engagingsurface terminating in an abutment engagable with said object restraintsurface and facing the direction of the second end of said shaft, saidplunger further defining a transitional angle forming a laterallyextending shoulder on at least one side of the plunger at a point wherethe configuration of the plunger changes from cylindrical towedge-shaped; biasing means disposed in said re-entrant bore biasingsaid plunger outwardly of said bore; said shaft being staked on at leastone side of the entrance of said re-entrant bore to provide an inwardlyextending marginal portion in an abutting relationship with saidshoulder, whereby said plunger is nonrotatably retained in said bore.25. (cancelled)
 26. (cancelled)
 27. A self-locking pin to be insertedthrough an aperture in at least one object wherein said objectterminates in a restraint surface to retain the pin in the aperture,said pin comprising: an elongated shaft including a first end and asecond end; a bore extending radially inwardly through the diameter ofsaid shaft; two plungers slidably disposed in said bore, each of saidplungers having a cylindrical portion and a wedge-shaped portion, aleading edge of said wedge-shaped portion being positioned closest tothe first end of said shaft, said leading edge of said wedge-shapedportion being proximate to said shaft surface and said wedge-shapedportion extending angularly upwardly of said shaft surface to define aramped engaging surface adapted for engagement with the object aperturesurface, said ramped engaging surface terminating in an abutmentengagable with said object restraint surface and facing the direction ofthe second end of said shaft, said plunger further defining atransitional angle forming a laterally extending shoulder on at leastone side of the plunger at a point wherein the configuration of theplunger changes from cylindrical to wedge-shaped; biasing means disposedin said re-entrant bore between said plungers, biasing said plungersoutwardly of said bore; said shaft being staked on at least one side ofthe entrance and exit of said bore to provide inwardly extendingmarginal portions in an abutting relationship with said shoulders,whereby said plungers are nonrotatably retained in said bore.